bighank

Was buying gallons of Mobil 1 5W30 at Wally World at $21.95 for a 5 quart container. Also have a newly acquired 1999 Cadillac DeVille which takes 10W30 when the sustained temperature is over 50 degrees F.

Looked at both containers.

Mobil 1 5W30 says it meets GM spec 4718M.
Mobil 2 10W30 DOES NOT

Cadillac recommends the heavier viscosity oil in the Northstar engine.
Why doesn't the Mobil 1 10W30 meet the same specs as their 5W30.? BIGHANK

B-ras

http://www.mobiloil.com/USA-English/..._1_10W-30.aspx

Quoted:

Mobil 1 10W-30 exceeds warranty requirements for gasoline engines where an API certified oil is specified. It meets:

* ILSAC GF-4 (API Certified - Starburst)
* API SM/SL
* GM 6094M/GM4718M
* Requirements for Diesel Powered Vehicles where an API CF or API CD is Recommended
* ACEA A1/A5, B1/B5


Maybe you picked up some of the Clean 5000? The damn bottles look a lot alike.

The Wrench

I'll bet the GM spec has some flowability-at-low-temp requirement that the 10w-30 won't meet. Of course, that's a moot point if you don't live in Fairbanks.

DG

Oldvetter

OR you could have picked up a bottle of 10W-30 Mobil 1 Extended Performance oil, this oil does not meet the "C5 Spec".

TEXHAWK0

I think that Mobil 1 quit referencing the GM spec and just added a statement like "selected as original equipment by major manufacturers like Chevrolet Corvette, Cadillac...".

Joe0121

Doesn't the 10W have some issues getting up and into the valve train, hence the 5w?

chriswtx

I run 10w40 in the summer, 10w30 in the winter...valvetrain has plenty of oil

ZeeOSix

That's what I was thinking to ...

bighank

They had lots of oils in the Frederick MD store. Hi mileage, 5000, you name it. On the back of the plastic jug the 5W30 label says it meets the lower GM spec (old vettes) and GM 4718M. The 10W30 jug says it meets the other less stringent spec, says NOTHING about GM4718M.
I know some of the other Mobil 1 products DON'T meet the newer vette spec but wonder why a slightly thicker oil doesn't. Been using 5W30 in the C5 but the techies in the Cadillac forums say that for Northstar engines before 2000 use 10W30 as it lubricates the cams better.
Incidentally the Caddy manuals dont even call for Mobil 1 just any kind of 10W30. BIGHANK

phoenixfoundmac

I use mobil1 10w30 year round and it's fine. As stated earlier, if you live in a decent climate it actually lubricates more consistently. The bottom line though is your really splitting hairs between the two. The only time I wouldn't recommend 10w30 is if you live somewhere in which the temperature is constantly 10 degrees or less.

bighank

Just went to the Mobil 1 website. You can look up the specs for any one of their products. The Mobil 1 10W30 spec sheet says it DOES meet the GM 4718M spec. Called the 800 number for info. Spoke to someone who said he is knowledgable about Mobil 1. He said that the labeling is done be the marketing division and could not say why the 10W30 product omitted the newer GM spec on the label. I said why would Mobil NOT want customers to know that a product meets a more severe spec. Several other Mobil 1 products do not meet this spec.
BIGHANK

B-ras

Hmmmm. If only someone had provided a link to that info in the first response in this thread. Oh, wait....

Dave68

I spoke to a Mobile 1 technical rep a couple of years ago and he told me that essentially, Mobil 1 10W-30 oil is no longer needed. Not only does the 5W-30 Mobil 1 pump-up to pressure faster at startup (even at 70 degrees F), it protects just as well as 10W-30 at very high temperatures. If you live in the Mojave desert, a 0W-40 would probably be a better choice than either of the other two, but the bottom line is that 10W-30 is not only unnessasary, but will contribute to shorter engine life in the long run.

B-ras

Thanks for that info.

I've wondered myself what the gain could be if the warm viscosity is the same. Even in SoFla, I guess I am better off sticking with the 5W30 for the startup protection, esp since my car is a DD.

lar66BB

Sometime in the past I heard. The 30w is the thickest it gets in cold
weather and the 5w is the thinest it gets in hot weather.

AU N EGL

0W is the thinest in hot weather or a very hot engine. and 50wt is the heaviest or thickest in normal conditions, but flows the best under performance driving or racing conditions where a 30wt is just too thin

Dave68

Skypilot797

Back in 1992 I had a C4. We agreed to run Mobile 5W-30W for 125,000 miles with only oil fliter and oil change's when the computer said it was time to change it. Usually around 7500 miles. After 2 years of driving, which my girl friend drove the heck out of it and me too, the engine was removed and inspected. The engine showed hardly any wear. It was an auto, and the trans did show signs of wear and it really was close to needng an overhaul. We got a new vette for doing this.
The thinner oil at start up, when cold, and this is what we were told, 5W versus 10W, allowed the engine to have less friction, which helps them meet gas mileage and emmissons requirements. Also, they wanted us, when oil temps were below 130 degress, not to go above 3,000 rpm due to valve spring requirements.
The engine never required any oil added to it between changes and after 100,000 miles or so, it did aquired a small leak out of the front of the manifold which fell on the distributor and caused a miss at high rpms.
What did wear out, and is off topic, was the computer chip on the key. Every so often, it thought you were trying to steal it, and required you to sit for 30 or so minutes, before you could reinsert the key and then start.

chriswtx

I have a 91'C4 I've had for 12 years. 118000 miles on non synthetic oil mostly Valvoline10W40 changed every 4000 miles. When I put the 400ci motor in I tore down the old motor, looked spotless inside, no wear on the bearings or stock cam and I ran the crap out of it all the time... Most of todays oils, synthetic and non synthetic are great products if you follow the correct maintenance schedules....